Blowout Preventer Ram Assembly Seal Relocation
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Solution Overview
Problem
Conventional blowout preventers (BOPs) face issues with seal damage during failures and ineffective sealing due to misalignment of rods with the main bore, leading to potential leaks and increased wellhead stack height when accommodating deviated polished rods, which complicates operations and safety.
Innovation Solution
The improved ram assembly design features seals located out of the path of threads, a pin-and-groove mechanism for rotational alignment with misaligned rods, and longer ram heads to prevent radial deflection, ensuring effective sealing and reduced risk of damage during failures, while allowing for direct integration with stuffing boxes without height increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ram assemblies are used with seals positioned near the threaded connection, then the structure is compact, but the seals are vulnerable to damage during failure events
Solution Approach 1:
The seal is extracted from its conventional position near the threaded connection and relocated to the forward end of the ram head, away from the bonnet-ram interface. This extraction removes the seal from the harmful zone where thread failure could damage it, while the seal continues to perform its sealing function on the rod.
Solution Approach 2:
The ram assembly is segmented into distinct functional zones: the threaded connection area for actuation, the intermediate area for structural support, and the forward end area for sealing. This segmentation allows each component to be optimized independently, with the seal positioned in the safest zone away from potential failure points.
2Adaptability or versatility
If the wellhead stack height is increased to accommodate deviated polished rods, then alignment with misaligned rods is improved, but the overall device height increases
Solution Approach 1:
The ram head is designed with rotational freedom allowed by a groove feature, enabling it to dynamically adjust its orientation to align with deviated polished rods. This dynamic adaptation eliminates the need for increased stack height, as the ram can rotate within its bore to accommodate various rod angles while maintaining compact overall dimensions.
Solution Approach 2:
The alignment function is merged into the ram assembly itself through the groove feature that permits rotation, rather than requiring a separate alignment mechanism or increasing the stack height. This integration achieves adaptability to deviated rods without adding to the overall device height.
3Device complexity
If shorter ram heads are used, then the device complexity is reduced, but radial deflection occurs under wellbore pressure
Solution Approach 1:
The ram head features an asymmetric groove configuration that provides rotational alignment capability while maintaining structural integrity. The groove geometry is specifically designed to allow rotation for alignment purposes while preventing excessive radial deflection under pressure, creating a non-uniform but optimized structural response.
Solution Approach 2:
The groove dimensions and orientation are carefully optimized to balance two competing requirements: allowing sufficient rotation for alignment with deviated rods while maintaining adequate stiffness to prevent radial deflection under wellbore pressure. The groove parameters are tuned to achieve the desired compromise between flexibility and stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances seal integrity, maintains effective sealing with misaligned rods, and reduces the risk of leaks and wellhead height increases, improving operational safety and efficiency by preventing seal damage and accommodating deviated rods without additional height or lifting requirements.
Implementation Method 1
a ram having a ram stem and ram head, the ram threadingly coupled to the ram shaft such that rotation of the ram shaft results in axial translation of the ram
Data Source
AI summary
An improved ram assembly for a blowout preventer having a design that permits the seals of the ram assembly to be located in the working area and out of the way of threads or other rough/jagged surfaces that could damage the seals in the event of failure of the blowout preventer, such as if the threaded connection fails and the rams are suddenly pushed outwards. The ram assembly can also have a pin-and-groove mechanism that permits the rams to rotate when in the closed/sealing position to account for a misaligned rod. Further, the ram heads of the ram assembly can have a sufficient length such that they remain supported by the bonnet and ram bores of the blowout preventer against radial deflection, relative to the ram bore, when in the closed position and exposed to wellbore pressure. Additionally, the actuators of the ram assembly remain axially stationary during use.